i dunno about the MH aye. when you start your flowering period with any light you'd wanna switch to 12/12 periods,and yea the 100w flo would do nicely in your mini fridge. 100w flo is more than i have at the mo and mine are doing alright (2 inches at the mo...buying more flueros soon)
I'm using only fleuros for my grow. ive been told that mh's and other powreful lights are far more expnsive to buy,run and run really hot so there's the risk of burning your plant if it's not fan-cooled or ventilated properly so yea thats why i'm all up for flueros - still grow nice plants though.Good luck with ur grow